1. Perform a clinical trial with divalproex sodium, consisting of an open phase followed by double blind discontinuation in children and adolescents with BD. hypothesis: Divalproex sodium will show safety and efficacy in symptom response as measured by the Clinical Global Impressions Scale (CGI) and the Young/Fristad Mania Scale after 8 weeks of monotherapy in a group of children and adolescents diagnosed with bipolar illness. 2. Identify potential predictors of treatment response. hypothesis: There will be a significant correlation between change in cerebral GA13A concentration as measured by Magnetic Resonance Spectroscopy (IHMRS), and change in treatment response to divalproex sodium as measured by the CGI after two weeks of therapy. We hypothesize that a higher cerebral GABA concentration will be significantly related to a decrease in symptom response to divalproex sodium.